The extraordinary story of a group of women held captive by a Maoist cult in London - including a woman from Northern Ireland - is the subject of a new documentary set to air next week.

Josephine Herivel from Belfast was one of three women held captive by Aravindan Balakrishnan in a small flat in Brixton, south London.

There, the women were subjected to decades of brainwashing, emotional and physical abuse.

Balakrishnan - known as Comrade Bala - convinced them that he had god-like powers and invented a supernatural force called 'Jackie' who, he said, could trigger natural disasters if his will was flouted.

The story only came to light in 2013, when Ms Herivel, the daughter of a Bletchley Park codebreaker and a musical prodigy in her childhood, called an anti-slavery charity asking for help to leave.

Specialist police then intervened and freed the women.

The women's remarkable story will now be told in a BBC2 documentary by acclaimed director Vanessa Eagle.

The programme, which tells the story of the collective from 1976 until the present, features interviews with two of the women who escaped, including 72-year-old Aisha Wahab, who was part of the group for 40 years, and Balakrishnan's daughter Katy Morgan-Davies, who was born in captivity.

Ms Herivel, who is still devoted to Balakrishnan, would not agree to take part in filming.

In the documentary, seen by the Daily Mail, Ms Morgan-Davies (now 33) describes how she and others in the cult were subjected to "shouting, cursing and physical violence" and how she was deprived of affection.

However, when asked if she hates her father, she responds: "No. I did used to hate him. I just felt completely powerless. But life is also very short. There is no time to be spent on hatred and anger."

She also expresses a wish to be reconciled with her father in the future "if he wants it".

On December 4, 2015, Balakrishnan was convicted of child cruelty, false imprisonment, four counts of rape, six counts of indecent assault and two counts of assault. He was finally jailed on January 29, 2016 for 23 years.

Speaking after his conviction, Ms Herivel told the Belfast Telegraph that she regretted contacting the charity.

She said she had spent three "joyful" days with Balakrishnan before he was jailed and that she was determined to clear his name.

"I was so happy to get the chance to speak to him," she said at the time. "He knows why I did it and is not angry with me. I spent three joyful days with him before he was wrongfully convicted.

"We talked a lot about our experience in the last two years. He is just so shocked by what has happened. He will survive prison and I will wait for him.

"I will rejoin him when he is released. I am just so angry about what has happened. It is a frame-up. He is such a good person. He is a genius. And I am going to do all I can to clear his name."

Ms Herivel, a former Methodist College student, first met the cult leader in the 1970s, when she was studying at the Royal College of Music in London. Shortly after their first meeting she dropped out of university and joined the cult.

She started working in a laundrette and shared her pay with the communist collective.